QPSK Modulator Baseband (Communications Blockset)

Modulate using the quaternary phase shift keying method

Library

PM, in Digital Baseband sublibrary of Modulation

Description

The QPSK Modulator Baseband block modulates using the quaternary phase shift keying method. The output is a baseband representation of the modulated signal.

Inputs and Constellation Types

If the Input type parameter is set to Integer, then valid input values are 0, 1, 2, and 3. If the input is m, then the output symbol is

where is the Phase offset parameter. In this case, the input can be either a scalar or a frame-based column vector.

If the Input type parameter is set to Bit, then the input contains pairs of binary values. The input can be either a vector of length two or a frame-based column vector whose length is an even integer. If the Phase offset parameter is set to pi/4, then the block uses one of the signal constellations in the figure below, depending on whether the Constellation ordering parameter is set to Binary or Gray.

Upsampling the Modulated Signal

This block can output an upsampled version of the modulated signal. The Samples per symbol parameter is the upsampling factor. It must be a positive integer. For more information, see Upsampled Signals and Rate Changes in Using the Communications Blockset.

Dialog Box

Input type: Indicates whether the input consists of integers or pairs of bits.
Constellation ordering: Determines how the block maps each pair of input bits to a corresponding integer. This field is active only when Input type is set to Bit.
Phase offset (rad): The phase of the zeroth point of the signal constellation.
Samples per symbol: The number of output samples that the block produces for each integer or pair of bits in the input.

Pair Block

QPSK Demodulator Baseband

QPSK Demodulator Baseband Quantizer Decode